Will the 'real' Jesus please stand up?

I have read several recent works of fiction that raise some interesting questions about Jesus. Cross Bones, by Kathy Reichs, examines the possibility that Jesus was not really raised from the dead, but rather lived to be an old man with a family who died on Masada in a Jewish revolt against the Romans. The Templar Legacy, by Steve Berry, also looks at the question of Jesus' resurrection, from the point of view of the ancient Templars, who tried to eradicate the Jews in the Holy Land in the Middle Ages. The Templars' secret, which has been hidden for ages, contains "proof" that Jesus did not rise from the dead, a notion that in the wrong hands could effectively wipe Christianity off the map. Finally, the Da Vinci Code, by Dan Brown, confronts us with the question of Jesus' humanity. Christians typically emphasize Jesus' divinity, often to the detriment of Jesus' humanity. Brown asks whether it is possible that Jesus was married with children, a question that often makes Christians uncomfortable.
While I enjoy reading "junk novels" as I call them, because they get me away from the scholarly reading I do most of the time, I also enjoy reading these books because they make me question the things I already believe. I think this helps me grow in my faith and my ways of thinking about the world, as well as giving me an opportunity to articulate my positions better.
The Gospels tell us much about Jesus' life, ministry, and character. They tell us that Jesus could heal the sick (Mt 15:21-28), raise the dead (Jn 11:17-44), and take on the religious authorities (Lk 5:17-26). The Gospels tell us that Jesus was crucified, was raised from the dead, and appeared to people in the flesh after his resurrection. Finally, the Gospels tell us that Jesus God in the flesh, the Incarnation. And yet, questions about who Jesus is abound.
Why is it so difficult to get a clear picture of who Jesus is? The disciples never really understood, the people whom Jesus healed never quite got it, the authorities that killed Jesus certainly didn't understand. Even today, if you ask 10 Christians who they think Jesus is, you will receive 10 different answers. Who is Jesus? Why do you think so many people have such a hard time answering this question with certainty?